DAX

Question 1

What does DAX stand for?

Answer 1

Data Analysis Expressions

Question 2

What is DAX?

Answer 2

A library of:
- Functions
- Operators
- Constants

that can be used in formulas

Question 3

Where is DAX used?

Answer 3

1. SSAS
2. Power Pivot in Excel
3. Power BI

Question 4

Commonly used operators in DAX

Answer 4

• ()
• +
• -
• *
• =
• <>

Question 5

How do you indicate the AND operator in a DAX expression?

Answer 5

??

Question 6

How do you indicate the OR operator in a DAX expression?

Answer 6

||

Question 7

How do you concatenate two values into one string?

Answer 7

+

Question 8

VAR syntax example

Answer 8

VAR VarName1=DAX Formula
VAR VarName2=DAX Formula

Return
Divide(VarName1, VarName2)

Question 9

VAR Example

Answer 9

VAR SalesAmount =
SUMX(Sales,
Sales [Unit Price] * Sales[Quantity])

VAR CustomerCount =
DISTINCTCOUNT (Sales[CustomerKey])

RETURN
DIVIDE (SalesAmount, CustomerCount)

Question 10

When should you use VAR?

Answer 10

Anytime you write a complex expression. This enhances formula readability.

Question 11

What are the benefits of using a VAR in a DAX formula?

Answer 11

• Easier to read
• Easier to debug
• Re-use formulas
• Avoid running formulas multiple times.
• To avoid extra columns in your column list that are intermediate calculations that will not be used independently

Question 12

What special characters do you use to comment DAX code?

Answer 12

For a single line
//

For a multi-line comment
/* … */

Just writing a really long sentence so it will left justify

Question 13

What is a calculated column?

Answer 13

• A new column added to an existing table
• Almost always applied row by row

Question 14

Calculated Column Syntax

Answer 14

CalculatedColumnName=
'TableName'[ColumnName1] OPERATOR 'TableName'[ColumnName2] 

Example
Total Sales =
‘Sales’[Quantity] * ‘Sales’[Unit Price]

Question 15

How does ADDCOLUMNS work?

Answer 15

• Automatically includes all columns from the table indicated in the Table argument
• Adds additional columns to that table by giving a column name as text and then the field name or an expression.

Question 16

When is a calculated column processed?

Answer 16

The calculation takes place during refresh time and the result is saved in memory.

Question 17

What do aggregate functions do?

Answer 17

Facilitate data aggregation across any business dimension. Examples are:
- Time
- Geography
- Product Categories
- Total Revenue

Functions such as
- Addition
- Subtraction

Question 18

ADDCOLUMNS syntax

Answer 18

ADDCOLUMNS(Table,
name1, expression1,
name2, expression2, …)

Just writing a long sentence to left justify

Question 19

ADDCOLUMNS example

Answer 19

Yearly_Sales_By_Color =
ADDCOLUMNS(
Sales,
“ProductColor”, RELATED(Products[Color]),
“Year”, RELATED(‘Date’[Year])
)